What is the recommended approach for diagnosing renal cell carcinoma, specifically regarding biopsy procedures?

From the Guidelines

The recommended approach for diagnosing renal cell carcinoma (RCC) involves a selective use of renal mass biopsy, prioritizing contrast-enhanced CT or MRI scans as the primary diagnostic tools, with biopsy considered in specific scenarios such as indeterminate imaging findings, non-surgical approaches, or metastatic disease requiring tissue diagnosis before systemic therapy. The decision to perform a biopsy should be based on the individual patient's risk factors, the size and characteristics of the renal mass, and the potential impact on management decisions. According to the European Association of Urology guidelines updated in 2022 1, a renal tumour biopsy should be performed before ablative therapy and systemic therapy without previous pathology, and a core biopsy technique is preferred over fine needle aspiration for histological characterization of solid renal tumours.

When a biopsy is indicated, the procedure should be performed using a coaxial technique, and a core needle biopsy is preferred due to its higher diagnostic yield and ability to provide architectural information, as supported by the American Society of Clinical Oncology clinical practice guideline 1. The use of 18-gauge needles under CT or ultrasound guidance, with 2-3 core samples, is recommended for optimal results, as suggested by the AUA guideline 1. This selective approach to biopsy balances the need for accurate diagnosis against potential complications, making it a safe and effective strategy for most patients with suspected RCC.

Key considerations in the diagnosis of RCC include:

• The use of multiphase contrast-enhanced CT of the abdomen and chest for diagnosis and staging, as recommended by the European Association of Urology guidelines 1
• The selective use of MRI to better evaluate venous involvement, reduce radiation, or avoid intravenous CT contrast medium, as suggested by the same guidelines 1
• The importance of individualizing treatment decisions for frail patients, weighing the risks and benefits of different approaches, as noted in the European Association of Urology guidelines 1
• The role of biopsy in specific scenarios, such as indeterminate imaging findings, non-surgical approaches, or metastatic disease requiring tissue diagnosis before systemic therapy, as supported by the American Society of Clinical Oncology clinical practice guideline 1 and the AUA guideline 1.

From the Research

Renal Cell Carcinoma Biopsy Approach

The recommended approach for diagnosing renal cell carcinoma, specifically regarding biopsy procedures, involves the use of percutaneous fine-needle aspiration cytology or core biopsy.

• The safety and accuracy of these procedures have been established in various studies 2, 3, 4.
• Percutaneous renal aspiration biopsy cytology is accurate, safe, and useful in establishing the diagnosis of renal cell carcinoma in patients with disseminated metastases or relative contraindications to surgery 2.
• The risk of tumor seeding appears negligible with the development of new biopsy techniques and wider experience with percutaneous probe ablation therapies 3.
• Significant bleeding is unusual and almost always self-limiting 3.

Indications for Renal Biopsy

There are established indications for percutaneous biopsy, including:

• Diagnosis of unresectable renal cell carcinoma
• Metastases
• Lymphoma
• Infection
• Diagnosis of benign neoplasms to prevent unnecessary surgery 4
• The number of indications is expected to expand further in the future 4.

Diagnostic Accuracy

• Needle core biopsy with or without fine needle aspiration appears to provide adequate specimens for an accurate diagnosis in more than 90% of renal masses 3.
• Cytopathologic findings can be true-positive, true-negative, false-negative, or false-positive, with sensitivity, specificity, and accuracy rates of 80%, 100%, and 87%, respectively 2.
• Immunohistochemistry can help in the diagnosis of tumor-to-tumor metastasis without the primary lesion biopsy 5.

Management of Renal Oncocytoma

• Percutaneous biopsy can diagnose renal oncocytoma, and treatment can be conservative with close follow-up 6.
• Initial management might be nonsurgical, and monitoring should not miss the time of conservative surgery 6.
• Initial tumor volume or fast tumor growth are indications for surgery, and partial nephrectomy is currently the technique of choice 6.